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Wolbachia, to control the spread of dengue

Director of the Eliminate Dengue Program Scott O’Neill and Secretary, Ministry of Health, Nutrition and Indigenous Medicine, Janaka Sugathadasa exchange notes of intent for a research partnership to seek a long-term solution to the dengue burden in Sri Lanka at the Foreign Ministry. Australian Foreign Minister Julie Bishop, Foreign Minister Ravi Karunanayake and Health Minister Dr Rajitha Senaratne look on.

Sri Lanka partnered with Monash University and the Australian Government last week to breed mosquitoes carrying Wolbachia, a low risk naturally occurring bacteria, to control the spread of dengue.

The project will be part of a comprehensive program by Australia to assist Sri Lanka effectively to control the seasonal vector borne disease which has hit the country hard and gone out of control due to a combination of factors, including a city solid waste management system that has recently gone haywire.

With nearly 100,000 cases and 290 deaths reported during the first seven months of 2017 alone, the Government is stretched to its limits trying to control the rising numbers of dengue patients, manage overflowing hospitals and prevent related deaths.

The Monash University’s Eliminate Dengue Program, has pioneered the use of Wolbachia bacteria to reduce the rates of dengue infection. Wolbachia naturally occurs in up to 60% of all insect species, including butterflies and dragonflies, but not the Aedes aegypti mosquito that transmits Dengue virus.

This common bacterium prevents the dengue virus being replicated in mosquitoes and therefore, transmitted between people. The bacterium has a similar effect on other viruses such as Zika, Chikungunya and yellow fever.

Australian Foreign Minister Julie Bishop was in the country last week to sign the agreement with Foreign Minister Ravi Karunanayake in this regard. The Australian Government is funding the Wolbachia pilot project and an agreement to contribute Aus $ 500,000 to the World Health Organisation (WHO) to support Sri Lanka’s fight against the deadly menace that has been plaguing the entire country, was signed at the Foreign Ministry on July 19.

The funds will help implement a comprehensive Dengue Prevention and Control Plan to enhance hospital triage and case management, cleaning, public awareness and surveillance systems through WHO.

According to the Monash University, the ’ Wolbachia bacteria can be used in a number of ways, including suppressing mosquito populations’. But the method used by the university’s Eliminate Dengue Program is unique because ‘it uses the bacteria to stop viruses from growing inside the mosquito and being transmitted between people’. The method is self-sustaining and has the potential to transform the fight against life-threatening viral diseases.

The Monash research team had successfully transferred Wolbachia from other insects into Aedes aegypti (Dengue) mosquitoes. Likewise, they will seed wild mosquito populations with Wolbachia in areas where dengue is endemic.

To find expected results the researchers do controlled releases of Wolbachia mosquitoes that then breed with wild mosquitoes.

Long term monitoring has shown that when a high proportion of mosquitoes in an area carry Wolbachia, local transmission of the disease has stopped.

“Following years of research into Wolbachia, our field trials have been met with widespread support from communities, governments and regulators,” the program announced adding that their field trials have been carried out since 2011. Sri Lanka is the seventh country to become part of the program. The other countries are Brazil, Colombia, Australia, Indonesia, Vietnam and India.

The first ‘city-wide’ trial of this research had commenced in northern Australia in 2014.

Independent research in the US and Australia so far has eliminated biological threats due to the release of the special mosquito. A research published in the US National Library of Medicine titled, ‘Risk Associated with the Release of Wolbachia-Infected Aedes aegypti Mosquitoes into the Environment in an Effort to Control Dengue,’ has concluded, “causing more harm by the release was considered a negligible risk”.

The Monash University’s Eliminate Dengue program is a not-for-profit collaboration and the university is currently working to make this novel approach more affordable and effective for large scale use in risk communities around the world.

Meanwhile, the Dengue Control Unit of the Health Ministry is also exploring the possibility of producing local Bti, the Cuban bacterium to destroy dengue larvae. Currently, the Bti is imported from China and a spokesperson said they have not called for fresh tenders to import Bti.

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